hairy-fruit spurge

Euphorbia cuphosperma is an herbaceous, annual plant with a taproot. It stands up to 20cm tall (~8 inches). The whole plant is hairy to various degrees. Leaf blades can vary greatly in shape, with margins which can be toothed or not. Beneath the flowers, whorls of leaf-like, green bracts often fan out, somewhat framing the flowers and fruits.

As seen on the iNaturalist map of documented observations, Euphorbia cuphosperma occurs in the southwestern states of Arizona and New Mexico. Surprisingly, it appears to be absent from northwestern Mexico, while the main body of its population occurs in mountainous central and northeastern Mexico, south into Oaxaca state. Plus there may be a report from highland Guatemala.

The genus name Euphorbia was published by Linnaeus in the first edition of his book Species Plantarum, in 1753 (p. 450). However, Linnaeus chose a pre-existing name, one going back at least as far as the Roman writer, scientist and army officer Pliny the Elder, who used this name for a plant in his book Naturalis historia or Natural History, dated 79AD. Pliny wrote that the name was coined by Juba I of Numidia, to honor a physician who had cured him of a disorder, and that physician's name was Euphorbus. Probably that plant was the Resin Spurge, Euphorbia resinifera. The species name cuphosperma is from the Greek kyphos, meaning "curved," and sperma for "seed" -- "curved seed."